Word processors actually do quite a lot. Word is host to multiple scripting environments and can do all kinds of useful stuff (the "useless bloat" you're always hearing about).
Before we had semantic markup on the Web, Word was doing something similar with meaningful styles that could drive document structure and whatnot. It's astonishing how often I see people either manually format headings (like, referencing a postit that says "heading: bold, 14pt") or use unstructured styles instead of the actual heading options.
Word will give you a document outline in a "slide out" window that populates based on your headings. It can be HUGELY USEFUL when you're building a longer, more intricate document, and yet it's rarely used properly. It's baffling.
The first time I used semantic style structure in a Word doc was in Word for DOS in about 1992.